MDEV-39440: replay context throwed a warning for a query after altering an index

The problem is that handler->multi_range_read_info_const() call in
check_quick_select() returned rows equal to HA_POS_ERROR, both during
context capture and replay. However, we never stored the ranges info
into the context when rows=HA_POS_ERROR. However, during replay, we try
to infuse stats for the given range, and since no match was found in the
context, we produced a warning.

Solution is to store range_info for all the ranges even when they get
HA_POS_ERROR number of rows.

Author: bsrikanth-mariadb

mysql-test/main/opt_context_replay_basic.result

@@ -272,5 +272,28 @@ set optimizer_replay_context='opt_context';
 EXPLAIN SELECT MAX(a) FROM t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+set optimizer_replay_context='';
+drop table t1;
+#
+# MDEV-39440: replay context doesn't work after altering the index
+#
+create table t1 (btn char(10) not null, key using HASH (btn)) engine=heap;
+insert into t1 values ("a"),("b"),("c"),("d");
+alter table t1 add column new_col char(1) not null, add key using HASH (btn,new_col), drop key btn;
+update t1 set new_col=left(btn,1);
+set optimizer_record_context=1;
+explain select * from t1 where btn="a";
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	btn	NULL	NULL	NULL	4	Using where
+select context into dumpfile "../../tmp/dump1.sql"
+from information_schema.optimizer_context;
+set optimizer_record_context=0;
+drop table t1;
+set optimizer_replay_context='opt_context';
+# Same query as above, must have same explain:
+explain select * from t1 where btn="a";
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	btn	NULL	NULL	NULL	4	Using where
+set optimizer_replay_context='';
 drop table t1;
 drop database db1;

mysql-test/main/opt_context_replay_basic.test

@@ -116,6 +116,34 @@ set optimizer_replay_context='opt_context';
 --echo # Same query as above, must have same explain:
 EXPLAIN SELECT MAX(a) FROM t1;
 
+set optimizer_replay_context='';
+--remove_file "$MYSQLTEST_VARDIR/tmp/dump1.sql"
+drop table t1;
+
+--echo #
+--echo # MDEV-39440: replay context doesn't work after altering the index
+--echo #
+create table t1 (btn char(10) not null, key using HASH (btn)) engine=heap;
+insert into t1 values ("a"),("b"),("c"),("d");
+alter table t1 add column new_col char(1) not null, add key using HASH (btn,new_col), drop key btn;
+update t1 set new_col=left(btn,1);
+
+set optimizer_record_context=1;
+explain select * from t1 where btn="a";
+select context into dumpfile "../../tmp/dump1.sql"
+from information_schema.optimizer_context;
+set optimizer_record_context=0;
+drop table t1;
+--disable_query_log
+--disable_result_log
+--source "$MYSQLTEST_VARDIR/tmp/dump1.sql"
+--enable_query_log
+--enable_result_log
+set optimizer_replay_context='opt_context';
+--echo # Same query as above, must have same explain:
+explain select * from t1 where btn="a";
+
+set optimizer_replay_context='';
 --remove_file "$MYSQLTEST_VARDIR/tmp/dump1.sql"
 drop table t1;
 

sql/opt_range.cc

@@ -12471,6 +12471,13 @@ ha_rows check_quick_select(PARAM *param, uint idx, ha_rows limit,
   ha_rows replay_ctx_max_index_blocks;
   ha_rows replay_ctx_max_row_blocks;
   bool replay_ctx_rc;
+  Optimizer_context_recorder *rec;
+  TABLE::OPT_RANGE *range= param->table->opt_range + keynr;
+  if (range)
+  {
+    range->max_index_blocks= HA_POS_ERROR;
+    range->max_row_blocks= HA_POS_ERROR;
+  }
   DBUG_ENTER("check_quick_select");
 
   /* Range not calculated yet */
@@ -12534,7 +12541,6 @@ ha_rows check_quick_select(PARAM *param, uint idx, ha_rows limit,
   param->quick_rows[keynr]= rows;
   if (rows != HA_POS_ERROR)
   {
-    TABLE::OPT_RANGE *range= param->table->opt_range + keynr;
     ha_rows table_records= param->table->stat_records();
     if (rows > table_records)
     {
@@ -12560,15 +12566,6 @@ ha_rows check_quick_select(PARAM *param, uint idx, ha_rows limit,
     range->max_row_blocks=
         MY_MIN(file->row_blocks(), rows * file->stats.block_size / IO_SIZE);
 
-    if (Optimizer_context_recorder *rec= param->thd->opt_ctx_recorder)
-    {
-      Range_print_enumerator_impl range_iter(param, idx, tree);
-      rec->record_multi_range_read_info_const(param->table->pos_in_table_list,
-                                              keynr, &range_iter, rows, cost,
-                                              range->max_index_blocks,
-                                              range->max_row_blocks);
-    }
-
     if (update_tbl_stats)
     {
       param->table->opt_range_keys.set_bit(keynr);
@@ -12597,6 +12594,14 @@ ha_rows check_quick_select(PARAM *param, uint idx, ha_rows limit,
     }
   }
 
+  if (range && (rec= param->thd->opt_ctx_recorder))
+  {
+    Range_print_enumerator_impl range_iter(param, idx, tree);
+    rec->record_multi_range_read_info_const(
+        param->table->pos_in_table_list, keynr, &range_iter, rows, cost,
+        range->max_index_blocks, range->max_row_blocks);
+  }
+
   /* Figure out if the key scan is ROR (returns rows in ROWID order) or not */
   enum ha_key_alg key_alg= param->table->key_info[seq.real_keyno].algorithm;
   if ((key_alg != HA_KEY_ALG_BTREE) && (key_alg!= HA_KEY_ALG_UNDEF))